1. Field of the Invention
This invention relates to containers, and in particular to security containers of the type requiring more than one operation to open them. Such containers include child-resistant containers that hold medicaments.
2. Description of the Related Art
Containers of pharmaceuticals or medicaments in solid dose form, such as tablets, pills or pellets, should be secure. More specifically, they should be child-proof or child-resistant, i.e. they should be difficult or impossible to open, by a simple operation.
One known type of security container has a screw-on lid that must be pressed firmly down before it can be unscrewed. Another type has a lid that must be correctly aligned before it can be prised off. However, a press-down lid may be very difficult for the aged or arthritic to operate, while the most common container requiring alignment (of respective marks on the lid and on the container body) may be too easily opened by an intelligent child.
U.S. Pat. No. 4,535,903 describes a security container in which the lid includes a retractable member. When retracted, there is no evident means of opening the lid; manipulation of the member, through a window in the lid, allows it to be pushed out from the lid, only then providing an evident tab, for opening the lid. Although this device should be easy to operate without it being readily evident how it can be opened, it suffers from several practical disadvantages. These disadvantages include ease of opening, e.g. by a child using teeth, or accidental opening, even when the retractable member is retracted, and the difficulty of balancing ease of retraction/opening, e.g. for the infirm or those with large fingers, with desired security. Further, a bulky lid is required, especially if the retractable member is to be adequately durable, with attendant problems of plastic shrinkage, and difficulty in moulding and manufacture, e.g. non-suitability for ultrasonic welding. This also means that the container must be sufficiently large that it will not generally be considered portable.
U.S. Pat. No. 3,901,407 discloses a locking cap assembly for a filler neck, e.g. of an automobile gasoline tank. The cap is releasable only after a partially-visible shaft is depressed, and this depression is only possible following correct setting of a combination lock. The numerals on the combination lock are visible at all times. The intention is to make opening of the cap impossible for all but the user who knows a pre-set combination.
WO-A-9526307 also discloses a container of the type requiring more than one operation to open. This container comprises a hollow body, a lid for the body, means for realisably engaging the lid such that the body is closed, and a marked member. The marked member is moveable between a first position at which the mark is hidden and said means engages the lid and a second position at which the mark is visible and the lid is releasable. This container is predicated on the non-visibility of marks indicating that there is a means of opening; by contrast, systems utilising a combination lock indicate that such means exist, but may be difficult to use successfully.